1. Field of the Invention
This invention relates to a semiconductor device comprising an electromigration prevention film and a manufacturing method thereof.
2. Description of the Related Art
A semiconductor device called a chip size package (CSP) has been described in Jpn. Pat. Appln. KOKAI Publication No. 2004-207306. This semiconductor device comprises a semiconductor substrate having a plurality of connection pads provided on its upper surface. On the upper surface of an insulating film provided on the semiconductor substrate, a plurality of wiring lines are provided so that they are electrically connected to the respective connection pads. Columnar electrodes are provided on the respective upper surfaces of connection pad portions of these wiring lines. A sealing film is provided on the upper surfaces of the wiring lines and the insulating film so that the upper surface of this sealing film is flush with the upper surfaces of the columnar electrodes. Solder balls are respectively provided on the upper surfaces of the columnar electrodes.
In the conventional semiconductor device described above, the sealing film directly covering the wiring lines is formed of an epoxy resin, so that there is such a problem that metal (copper) ions in the wiring lines diffuse into the sealing film due to the generation of electromigration, which is one factor of a short circuit caused between the wiring lines.
Furthermore, an epoxy resin in which fillers made of, for example, silica may be used as the material of the sealing film. In such a semiconductor device, the wiring lines may be mechanically damaged by the fillers. In preventing the breaking of the wiring lines due to the mechanical damage, there is a problem of a limit in the miniaturization of the wiring lines.